Conventionally, regarding a ranging system using wireless communication, as a technique for the purpose of “transmitting and receiving packets between a source and a recipient and ranging and positioning using its respondent procedure”, such a system is proposed that “when a radio set 1 transmits a packet to a radio set 2, a communication partner, the radio set 2 transmits a packet without fail after an elapse of an integral multiple of a unit time from the time of a packet detection. The radio set 1 measures the time from the transmission of the packet by itself to the packet detection of the radio set 2 using a counter. Then, converting the time subtracting the time from the packet detection of the radio set 2 to the transmission and processing time of the radio set 1 itself from a measurement time into a propagation distance to the radio set 2, a communication partner, to achieve ranging”. (Patent Document 1)
As a technique with a purpose such that “to provide a controller for a human body detection air-conditioning air nozzle capable of detecting a plurality of human bodies existing at arbitrary locations to fairly and efficiently supply an air-conditioned air is an object”, it is proposed such that “An air-conditioned air nozzle 1 sends an air-conditioned air to an arbitrary direction with a variable rotation angle in both forward and reverse directions. Human body detection sensors 2a to 2n are disposed in order that surround the above by dividing a circumference into the plural without overlapping a detection area. Then, a controller for a human body detection air-conditioned air nozzle can be obtained capable of fairly and efficiently supplying an air-conditioned air to various human body existing conditions by a controller collectively processing signals from these sensors.” (Patent Document 2)
As a technique with a purpose such as “to provide an equipment management apparatus for automatically detecting partitions even if there is any and automatically setting a candidate for an equipment management group in consideration of the partition upon detecting it”, such an apparatus is proposed that is “provided with position calculation means 22 for calculating each position of each equipment 10 based on a mutual measurement distance of a plurality of equipment 10, cover assumption means 23 for calculating a distance between each equipment based on the position of each equipment 10 calculated by position calculation means 22 to assume a position of a cover wall based on an error between the calculation distance and measurement distance between each equipment, and operation setting reasoning means 28 for setting a candidate of an operation group based on a position of each equipment 10 derived by cover assumption means 23 and an assumed position of the wall.” (Patent Document 3)    Patent Document 1 Japanese Unexamined Patent Application Publication No. 2004-258009    Patent Document 2 Japanese Unexamined Patent Application Publication No. 2001-304653    Patent Document 3 Japanese Unexamined Patent Application Publication No. 2006-217390